The aim of this research is to contribute to the understanding of olfaction in the malaria vector mosquito Anopheles gambiae, especially as it pertains to host choice and vectorial capacity. Malaria continues to be a serious threat and demands focused investigation. The experiments outlined in this proposal seek to characterize one of the molecular components of olfaction in A. gambiae, an arrestin gene, AgArr1. As arrestins are known to desensitize heptahelical receptors (such as odorant receptors), these studies will initially investigate the role of arrestin genes in olfactory pathways using established mutants in the well-characterized Drosophila melanogaster model system. Behavioral and physiological paradigms including odor-baited traps and electroantennogram (EAG) recordings will be employed to identify and define olfactory phenotypes associated with the loss of insect arrestins. Subsequently, transgenic expression of AgArr1 in Drosophila will be performed to test the ability of the mosquito gene to compensate for these mutations and rescue the phenotype. In order to answer whether AgArr1 plays a similar role in mosquito olfactory pathways, double-stranded RNA interference gene silencing techniques will be utilized to decrease AgArr1 expression in A. gambiae for phenotypic analysis by EAG. These experiments will not only define olfactory deficits associated with loss of arrestin expression in insects, but also examine potential targets for antimalarial vector control.